--- /dev/null
+! { dg-do run }
+!
+! PR fortran/51972
+!
+! Contributed by Damian Rouson
+!
+! TODO: Remove the STOP line below after fixing
+! The remaining issue of the PR
+!
+
+module surrogate_module
+ type ,abstract :: surrogate
+ end type
+end module
+
+module strategy_module
+ use surrogate_module
+
+ type :: strategy
+ end type
+end module
+
+module integrand_module
+ use surrogate_module
+ use strategy_module
+ implicit none
+
+ type ,abstract, extends(surrogate) :: integrand
+ class(strategy), allocatable :: quadrature
+ end type
+end module integrand_module
+
+module lorenz_module
+ use strategy_module
+ use integrand_module
+ implicit none
+
+ type ,extends(integrand) :: lorenz
+ real, dimension(:), allocatable :: state
+ contains
+ procedure ,public :: assign => assign_lorenz
+ end type
+contains
+ type(lorenz) function constructor(initial_state, this_strategy)
+ real ,dimension(:) ,intent(in) :: initial_state
+ class(strategy) ,intent(in) :: this_strategy
+ constructor%state=initial_state
+ allocate (constructor%quadrature, source=this_strategy)
+ end function
+
+ subroutine assign_lorenz(lhs,rhs)
+ class(lorenz) ,intent(inout) :: lhs
+ class(integrand) ,intent(in) :: rhs
+ select type(rhs)
+ class is (lorenz)
+ allocate (lhs%quadrature, source=rhs%quadrature)
+ lhs%state=rhs%state
+ end select
+ end subroutine
+end module lorenz_module
+
+module runge_kutta_2nd_module
+ use surrogate_module,only : surrogate
+ use strategy_module ,only : strategy
+ use integrand_module,only : integrand
+ implicit none
+
+ type, extends(strategy) ,public :: runge_kutta_2nd
+ contains
+ procedure, nopass :: integrate
+ end type
+contains
+ subroutine integrate(this)
+ class(surrogate) ,intent(inout) :: this
+ class(integrand) ,allocatable :: this_half
+
+ select type (this)
+ class is (integrand)
+ allocate (this_half, source=this)
+ end select
+ STOP 'SUCESS!' ! See TODO above
+ end subroutine
+end module
+
+program main
+ use lorenz_module
+ use runge_kutta_2nd_module ,only : runge_kutta_2nd, integrate
+ implicit none
+
+ type(runge_kutta_2nd) :: timed_lorenz_integrator
+ type(lorenz) :: attractor
+
+ attractor = constructor( [1., 1., 1.] , timed_lorenz_integrator)
+ call integrate(attractor)
+end program main
+
+! { dg-final { cleanup-modules "surrogate_module strategy_module integrand_module runge_kutta_2nd_module" } }